Use of CED's, such as e.g. coiled tubing, sourced from a hydraulically operated reel is known in oil and natural gas exploration and production operations. These tubings, generally refer to metal pipes, e.g. made from steel, with diameter ranging between 1 inch and 4 inches (2.54-10.12 centimeters), or suitably within the range 1.5 to 3.5 inches (3.81-8.89 centimeters). Such tubing may typically have a wall thickness of 5-15% of the tubing diameter, although a different wall thickness range may applied dependent on the use of the tubing. It is also known, that coiled tubing can perform many different oil well operations, and these include use in interventions in oil and gas wells, and use as production tubing in gas wells as well.
Application of such coiled tubing in oil and gas operations involves deploying the tubing as support for drill tools for inserting those tools into boreholes or for retrieving those tools from boreholes. Such tools can be packers, valves, sleeves, sensors, plugs, gauges and so on, which have to be run into and retrieved from the boreholes. These tools may find use for servicing the well.
The operations as stated in the preceding paragraph are done through lubricator string sections and those sections serve as a sluice for undertaking such operations.
How a lubricator string functions for insertion of tools into the well and for retrieval of the same therefrom, are all common knowledge in the art and will not be elaborated on any further.
How to handle a tubular piping system is e.g. described in Norwegian Patent Application Nr. 20131601, filed on 3. Dec. 2013 and entitled PIPE HANDLER, the disclosure of which is hereby incorporated by this text reference.
In the above context, telescopic injector masts are also known which extend from a base up to a substantial height and supports a coiled tubing conveyor apparatus at its top end and a lubricator string suspended from the coiled tubing conveyor apparatus. Upon insertion into the wellhead, prior thereto coiled tubing is stabbed through the coiled tubing conveyor apparatus, and thereafter conveyed through the lubricator string, which is located just above the borehole. The purpose is to insert tools into the borehole as stated before. The pulling operation of coiled tubing takes place in just the opposite direction of retrieving the tools from the borehole.
As stated before, injector masts for ensuring lifting of tubing conveyor apparatus (injector heads) to undertake the operation as stated in the preceding paragraph are already known. For example, U.S. Pat. No. 7,077,209 teaches a telescopic mast having two arms, which can telescopically rise for supporting a tubing gripper conveyor apparatus at a height and positioning it above the wellhead. The mast is pivotally mounted to a vehicle.
The above document and likewise prior art known in the art does not have any teachings for rapid, accurate and safe assembling of lubricator strings below the injector head and aligning these above the well head, thereby ensuring smooth passage of the coiled tubing.
Furthermore, no teachings exist in prior art on how to precisely receive the coiled tubing from any direction and to pass it through the coiled tubing conveyor head, and simultaneously ensuring that the coiled tubing conveyor head is appropriately positioned above the well head.
A technology to meet the need of providing said teachings, which are lacking in prior art, and other associated needs, is described in Norwegian Patent Application Nr. 20131640 filed on 10 Dec. 2013 and entitled HANDLING SYSTEM, the disclosure of which is hereby incorporated by this text reference, the handling system described therein being equipped with a telescopic mast, mounting a tubing conveyor apparatus (or an injector head) at its top end, which mast can swivel about a vertical axis for correct injection or pulling out of the continuous tube from any direction, through the tubing conveyor apparatus and through lubricator strings. The mast also has a handling device for efficiently and rapidly assembling and disassembling lubricator strings on and from the top of the wellhead and for proper positioning and alignment of the strings beneath the tube conveyor head.
In the context of the prior art described above it has been recognized that gripping elements of the tubing conveyor apparatus should be related to a movable carrier and a gripper shoe which is removably attached to such carrier.
The disclosure of U.S. Pat. No. 6,173,769-B1 describes a coiled tubing conveyor apparatus exhibiting inter alia a pair of continuous, segmented drive belts, each belt with a plurality of carriers carried by a pair of drive chains, each carrier having front and back sides, and means for removably attaching a tubing gripper shoe to a front side of the carrier, an elastomeric pad with high spring rate being sandwiched between a gripper shoe base and the carrier to allow the gripper shoe to resiliently “float” on the carrier. The purpose of the elastomeric pad is to allow the gripper shoe to automatically make small adjustments in its alignment with coiled tubing as it engages the tubing, thus providing a more even distribution of gripping forces across the shoe. The elastomeric pad also accommodates manufacturing tolerances that result in slight variations in the distances between an elongate counter-force member, typically known as a “skate” in the art, on which rollers on the carriers ride, and the centerline of the tubing to be gripped. Preferably, only gripper shoes are used that have fixed shapes conforming to a normal shape of the tube or pipe, and that surround substantially half of the circumference of the tubing. As an outset, fixed shaped shoes cause the tubing to retain its normal shape when conveyed through the conveyor head and enhance the gripping ability, provided that e.g. the tubing diameter has not changed substantially.
EP 0507280 shows an injector having a load cell. The injector head is attached to the load cell on one side and a hinge on the other side. Consequently, the injector head will tilt slightly about the hinge and inflict a force on the load cell. The tilting movement required to sense the load is very small. There is no indication that the hinge is adapted to allow for any significant degree of tiling beyond what is required to trigger the load cell.
If the hinge had allowed for larger tilting, such as beyond 1°, this would result in a sever pull and push force inflicted on the coiled tubing over the short stretch between the lowermost gripper and the lubricator. This is not desirable.
US 2006/081368 shows an injector where each half of the injector head is hingedly attached to a frame. Thereby the halves can be swung outward from one another so that the coiled tubing can be thread through the injector head with ease. If the halves are allowed to tilt about these hinges when the injector is operating, the grippers will be forced to glide relative to the coiled tubing, which in turn results in great wear of the coiled tubing.
U.S. Pat. No. 6,209,634 shows an injector similar to US 2006/081368, having the same features.